User Manual
Chapter 7
GFK-1742F
Jan 2020
Programmed Motion
211
7.7.8
Feedrate Override
Some applications require small modifications to a programmed velocity to handle outside
changes. A Rate Override %AQ immediate command, which is sent to the DSM through
ladder logic, allows changes to a programmed feedrate (velocity) during program
execution. (Details about the Rate Override command are found in Chapter 5.) When a
program begins executing, the override rate is initially set to 100%. Thus, changes to
feedrate before the execute program bit is turned ON will be ignored. However, a rate
override commanded on the same sweep as an execute program bit will be effective.
A percentage can be assigned to the feedrate override of from 0% to 120%. When a Rate
Override is commanded, the DSM314 internally multiplies the feedrate percentage by
programmed velocity to obtain a new velocity. If the axis is moving, the current move’s
Jog
Acceleration Mode is used to change velocity to the new velocity. All future move velocities
will be affected by the feedrate change. Note that when a feedrate of 0% is applied, no
motion will be generated until a new feedrate is commanded. Also note the Moving %I bit
stays ON when the feedrate is 0%.
Rate Override has no effect on non-programmed motion such as Jog, Find Home, or Move
at Velocity.
Example 17: Feedrate Override
During execution of this program, feedrate changes of + or -10% are commanded. Dotted
lines indicate -10%, dashed lines in10%.
Figure 89: Feedrate Override Example